Biotech drugmaker Amgen is reportedly close to buying cancer drugmaker Onyx Pharmaceuticals for about $10.5 billion.

The New York Times reported Saturday that Amgen Inc. would buy Onyx for $125 per share. It cited people who had been briefed on the matter. The two companies declined to comment.

Amgen's drugs include Prolia for osteoporosis, Enbrel for rheumatoid arthritis and skin disorders, and Neulasta and Neupogen for fighting infection in cancer patients. The Thousand Oaks, Calif., company reported $17.27 billion in revenue in 2012.

Onyx Pharmaceuticals Inc. markets a liver and kidney cancer pill called Nexavar through a partnership with Bayer AG. Sales totaled about $861 million in 2012, and Onyx received $288 million in revenue from those sales. In July the regulators approved Onyx's Kyprolis as a treatment for multiple myeloma, a type of blood cancer.

Multiple myeloma causes tumors to grow in the bone marrow, preventing the production of normal blood cells. The FDA approved Kyprolis for patients who have already been treated with at least two other multiple myeloma drugs, and Onyx is conducting other trials to win broader marketing approval. Onyx and Bayer are also testing Nexavar as a treatment for breast cancer.

The South San Francisco company rejected an offer from Amgen of $120 per share in June. In the days after that offer became public, Onyx shares climbed as high as $136.87. The stock closed at $116.96 Friday.

A bid worth $125 per share would represent a 44 percent premium to Onyx's closing price on June 28, before reports of Amgen's initial bid.

Onyx and Pfizer Inc. are studying a drug called palbociclib as a treatment for breast cancer.

The Onyx drugs would add to Amgen's pipeline of new drugs. In the first half of 2014 Amgen expects to announce late-stage testing data for three experimental drugs. The products are being studied as treatments for skin cancer, recurrent ovarian cancer and high LDL, or bad cholesterol, that doesn't respond to pills such as Lipitor.